Magnetic switch



MaylS, 1934. J. a. TAYLOR n AL MAGNETIC swITcH Filled May s1, 1932 ATTORNEYS` `Patented May 15, 1934 UNITED STATES 1,959,115 MAGNETIC SWITCH James B. Taylor and Warren F. Weathers, De-

' troit, Mich., assignors of one-fourth to James W. Sibley, Detroit, Mich. f

Application May 31, 1932, Serial No. 614,330. 6 Claims. (Cl. 200-86) The present invention pertains to a novel magnetic switch designed particularly to be embedded in a road or pavement and operated by a motor vehicle riding over the same. Such a switch is intended to be used for closing an electrical circuit and operating certain electrical apparatus when the motor vehicle comes within a certain distance of the switch. For example, the switch may be used to operate an alarm or turn on a light. One of the.contacts ofthe switch is a xed member, andthe other contact is carried on an end of a magnetized, balanced arm, which end is attracted into engagement with the fixed contact to close the circuit.

Another feature of the invention lies in the novel manner of balancing the arm. This arm is pivotally suspended preferably from a pivot at an off center point, providingy lever arms of unequal length at opposite sides of the pivot, and the balance is restored by means of an adjustable weight mounted on the shorter arm. The shorter lever arm is weighted to balance the longer lever arm.' A vehicle riding over the device attracts the longer lever arm to close the electrical circuit, and because of the unequal lengths of the arms, a greater pull is exerted on the longer arm than on the shorter lever arm. l s

The invention is fully disclosed by way of example in the following description and in the accompanying drawing, in which- Figure 1 is a vertical longitudinal section of the device;

Fig. 2 is a plan view with the cover removed; Fig. 3 is a section on the line 3-3 of Figure l; Fig. 4 is a detail vertical section of the pivot suspension; and

Fig. 5 is a wiring diagram. C Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

The device-is embodied within a non-magnetic box 1 having Aa removable non-magnetic cover 2, and these parts are suitably embedded in a pavement 3, after assembly, as illustrated in Figure 5.

The working parts are supported beneath the cover 2, and in this connection an inverted U- shaped bracket or stirrup 4 is secured to the base of the box by means of rivets 5. A clip 6 is passed through the top of the stirrup and soldered thereto as indicated by the numeral 7 1n Figure 4. Into the clip is inserted. one end of a depending, delicate flat metal spring 8 which is fastened by crimping the sides of the clip 19 by means of a 55 suitable tool. A similar clip 10 is applied to the lower end of the spring 8 and likewise clipped thereto at 11.

An armf12 is attached to the lower end of the clip 10 by solder 13, and it will be seen in Figure 1 that the attachment is made at an off center 50 point of the arm, thereby providing lever arms of unequal lengths at opposite sides of the point of suspension. 'Ihe manner of attachment, consisting in crimping the clips to the flat spring 8 and soldering the clips only to the stirrup 4 and 65 arm 12, avoids the use of .solder close to the spring, whereby the latter might become covered with solder and affected in its sensitiveness. The balance of the arm 12 is restored by means of a weight 14 of non-magnetic material, such as lead, 70 applied to the shorter lever arm and secured inA the proper position of adjustment by means of set screws 15.

To the end wall of the box 1 adjacent the end of the longer lever arm is secured a bracket 16 75 in which is mounted a binding post 17 insulated from the bracket by a bushing 18. The post is formed with a contact point 19 of suitable material such as tungsten, and directly beneath this point a copper clip 20 is mounted on the arm 12. 80 The clip 20 also carries a suitable contact point '21 for engagement with the point 19 under certain conditions as will presently be described.

A conductor 22 is secured to the binding post 17 and passes through a hole 23 in the adjacent side wall of the box 1. The other side of the circuit is represented by a binding post 24 secured to the bottom of the box 1 and having another conductor 25 fastened thereto. A strip 26 of good conducting metal, such as copper, is applied to the arm 12 and secured at its ends to the clips 10 and 20. In the passage of current between these clips, as will presently appear, the current flows through the strip 26 rather than the arm 12, thereby avoiding any interference with the magnetized condition of this part of the arm by the flow of current therethrough.

It may be assumed for the present that the conductors 22l and 25 represent a circuit which is made and broken at the contact tips 19 and 100 21. The arm 12 is so balanced on its pivot that these tips are normally out of contact and the circuit open. When a vehicle rides over the box 1 in the pavement 3, the magnetic parts thereof attract the magnetized end of the arm 12 to- -wards the contact 19, whereby the circuit is closed. The current ows from the conductor 22 through the port 17 and tips 19, 21 and along the strip 26 to the spring 8 and cover 2, to wh1ch no the other side of the circuit is connected through the box 1.

Current for the operation of the device is taken -from a pair of mains 27 which are connected to the intake terminals of a transformer 28 by conductors 29. The output terminals of the transformer are connected respectively to the conductors 22 and 25, and in the conductor 25 is inserted an electro magnet 30.

The device to be ultimately operated by the engagement of the contacts 19 and 21 is here shown as an electric gong 31 which may, for example, be used to attract the attention of a gas station attendant when a motor car rides over a box 1 embedded in the pavement near any one of the pumps. The balancing of the magnetized arm is so delicate that the chassis of the car alone is sufficient toV attract the longer lever arm, that is, the motor car need not carry an auxiliary magnet. This is merely illustrative of any electrical device which is to be operated when a motor vehicle comes to a certain predetermined position.

A swinging switch arm 32 is positioned to be attracted by the solenoid when the latter is energized and thus brought into engagement with an adjacent fixed contact 33. The latter is connected to the line 22 by a conductor 34 which passes through the terminals of the electrical device 3l, and the pivoted end of the switch arm 32 is joined to the other line 25 by a conductor 35. Thus, the energizing of the electromagnet by the engagement of the contacts 19 and 21 causes the switch 32, 33 to close and the electrical device 31 to operate.

Although a specific embodiment of the inven tion has been illustrated and described, it will -,b'e

understood that variJus alterations in the details of construction may be made without departing from the scope of the invention, as indicated by the appended claims.

What we claim iszy 1. A magnetic switch comprising a supporting bracket, a at metal spring attached to and suspended therefrom, a balanced arm attached to and suspended from saidgspr'ing ,fand having one end magnetized, a contact member over said end, and means for conducting current to said end and to said contact.

bracket, flexible means depending from said bracket, a bar magnet attached to said flexible means at a point between its ends and supported thereby with its longitudinal axis in a horizontal plane, a contact member spaced above one end of said bar, and means for conducting current to said end and to said contact.

4. A magnetic switch comprising a supporting bracket, exible means depending from said bracket, a bar magnet attached to said flexible means at a point nearer one end of the bar than the other, a non-magnetic weight mounted on said end and balancing said arm to maintain its longitudinal axis in a horizontal plane, a contact `member' spaced above said other end, and means for conducting current to said other end and to said Contact.

5. A magnetic switch comprising a supporting bracket, a iiat metal spring attached to said bracket and depending therefrom, a bar magnet connected between its ends to said spring and supported thereby with its longitudinal axis inA a horizontal plane, a contact member spaced above one end of said bar, and means for conducting current to said end and to said magnet.

-6. 'A magnetic switch comprising a supporting bracket, a leaf spring connected to and depending from said bracket, a bar magnet connected to said spring at a point nearer one end of the bar than the other, a non-magnetic weight on said other end and adapted to balance said bar and maintain it with its longitudinal axis in a horizontal plane, a contact member spaced above said other end, and means for conducting current to said other end and to said contact.

JAMES B. TAYLOR.

WARREN F. WEATHERS. 

